Battery Insulation Resistance Measurement With Adaptive Switching Cycles
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Solution Overview
Problem
Conventional methods for measuring insulation resistance in high power, high voltage batteries take a long time and are inaccurate in diagnosing the breakdown point due to varying Y capacitance values among vehicles.
Innovation Solution
An insulation resistance measuring device that includes a first and second voltage distribution unit, switches, and a controller to adjust switching cycles based on maximum Y capacitor values, resetting cycles upon voltage saturation, and terminating operations when abnormal voltage events occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum Y capacitance value is used for calculation, then the insulation resistance measurement can be performed, but the measurement time becomes excessively long and the diagnosis of breakdown point is delayed
Solution Approach 1:
The patent applies dynamics by making the switching cycle adjustable rather than fixed. The controller dynamically reduces the switching cycle from an initial value to a current value that is shorter than the time required for voltage saturation, optimizing the measurement process in real-time based on system response
Solution Approach 2:
The patent implements feedback by monitoring whether the first and second voltages reach saturation during the on-period of the switches. Based on this feedback, the controller adjusts the switching cycle - resetting to initial cycle if saturation isn't achieved, or maintaining reduced cycle if saturation is achieved, thereby optimizing measurement time while ensuring accuracy
2Productivity
If the switching cycle is reduced to shorten measurement time, then productivity improves, but the voltage may not reach saturation leading to inaccurate measurement
Solution Approach 1:
The switching cycle is made dynamic rather than static. The controller adjusts the switching cycle based on whether voltage saturation is achieved, allowing the system to operate at faster cycles when conditions permit while ensuring accuracy when needed
Solution Approach 2:
The patent changes the timing parameter (switching cycle) based on system response. By monitoring voltage saturation and adjusting the switching cycle accordingly, the system optimizes the balance between measurement speed and accuracy
3Reliability
If conventional switch alternation method is used, then the insulation resistance can be calculated, but the breakdown point diagnosis is delayed due to long calculation time
Solution Approach 1:
The patent applies skipping by rushing through the voltage saturation process. By reducing the switching cycle to be shorter than the saturation time and using feedback to detect when saturation is achieved, the system skips unnecessary waiting time while still obtaining accurate measurements for breakdown point diagnosis
Data Source
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AI summary
An insulation resistance measuring device as an insulation resistance measuring device between a battery including a plurality of battery cells and a ground includes: a first voltage distribution unit, which distributes a voltage between the positive electrode of the battery and the ground; a second voltage distribution unit, which distributes a voltage between the negative electrode of the battery and the ground; a first switch SW1 connecting the positive electrode of the battery and the first voltage distribution unit; and a second switch SW2 connecting the negative electrode of the battery and the second voltage distribution unit, wherein when the first voltage, which is an output of the first voltage distribution unit, is saturated during the on-period of the first switch SW1, or the second voltage, which is an output of the second voltage distribution unit, is saturated during the on-period of the second switch SW2, the current switching cycle of the first and second switch from the previous switching cycle is reduced.